Sulfite esters as preservatives for black and white developing agents

ABSTRACT

A METHOD OF AND SOLUTION FOR BLACK AND WHITE DEVELOPING OF SILVER HALIDE GELATIN LAYERS WITH THE USE OF A BATH THAT INCLUDES A CONVENTIONAL BLACK AND WHITE DEVELOPING AGENT OR AGENTS AND OTHER CONVENTIONAL CONSTITUENTS SUCH AS RESTRAINERS, ANTI-FOGGANTS, SEQUESTRANTS, SILVER HALIDE SOLVENTS AND GELATIN HARDENERS AND WHICH FOR THE PRESERVATIVE USES A SULFITE ESTER SELECTED FROM THE CLASS CONSISTING OF 1,2ETHYLENESULFITE; 1-METHYL-1,2-ETHYLENESULFITE; 1,2-DIMETHYL1,2-ETHYLENESULFITE; 1,3-PROPYLENESULFITE AND DIMETHYLSULFITE IN THE PRESENCE OF AN ALKALI IN AN AMOUNT SUFFICIENT TO PROVIDE FOR THE BATH A PH OF AT LEAST 8.

United States Patent O 3,713,826 SULFITE ESTERS AS PRESERVATIVES FOR BLACK AND WHITE DEVELOPING AGENTS Donald J. Sykes, Upper Saddle River, N.J., Harry Kroll, Warwick, R.I., and Theron R. Finch, Northvale, N.J., assignors to Philip A. Hunt Chemical Corporation, Palisades Park, NJ. No Drawing. Filed Nov. 16, 1970, Ser. No. 90,025

Int. Cl. G03c 5/30 US. Cl. 96-664 9 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION (1) 'Field of the invention A black and white developing or developing/ fixing bath which includes a conventional black and white developing agent, conventional additives and as a preservative certain sulfite esters in the presence of an alkali in an amount sufiicient to obtain a bath pH of at least 8.

(2) Description of the prior art Black and white developing baths and monobaths (developer/fixers) customarily have employed preservatives for preventing oxidation of the black and white developing agents. The preservatives heretofore conventionally employed were alkali metal sulfites, alkali metal bisulfites, hydroxyalkylamine-sulfur dioxide addition products and ascorbic acid and its isomers. The alkali metal sulfites and/ or bisulfites are effective preservatives but are of limited solubility in water. Concentrates which contained high proportions of hydroxyalkylamine-sulfur dioxide addition products tended to have a high viscosity and, hence, were difficult to pour and measure accurately and to mix smoothly and evenly with diluents such as water.

Moreover, some developers containing such prior art preservatives tended to induce a reaction between the preservatives and other constituents of the bath, so that the developer solutions were not highly stable. Specifically, there tended to be a reaction between such prior art preservatives and prior art gelatin hardening agents, viz, aldehydes and dialdehydes.

SUMMARY OF THE INVENTION (1) Purposes of the present invention It is an object of the present invention to provide a black and white silver halide photographic processing preservative for developing agents which is not subject to any of the foregoing drawbacks and which can be used to provide liquid developer and developer/fixer concentrates, replenishers and working solutions of all types that are highly stable because it does not tend to react with other constituents of the developers and developer/fixers and replenishers, the preservative even in highly concentrated form being sufiiciently non-viscous to pour accurately and with ease and to mix smoothly and readily with diluents such as water.

3,713,826 Patented Jan. 30, 1973 It is another object of the present invention to provide for a black and white silver halide photographic developer a developing agent preservative which is at least as eflicient in its operation as conventional sulfite preservatives, i.e. which will supply on a weight percentage basis sufficient available sulfite ion in water solution to act as a preservative for the black and white developing agent with out requiring the use of an uneconomically large amount of the preservative.

Other objects of the invention in part will be obvious and in part will be pointed out hereinafter.

(2) Brief description of the invention The invention relates to the developing of photographic silver halide layers in an aqueous bath containing a black and white developing agent the said layers being present in the form of silver halide-containing gelatin coating supported on film or paper. Essentially, the invention constitutes treating such coatings with a bath including as the preservative a sulfite ester selected from the group consisting of 1,2-ethylenesulfite; l-methyl-l,2-ethylenesulfite; l,Z-dimethyl-1,2-ethylenesulfite, 1,3-propylenesulfite and dimethylsulfite, and also including an alkali in an amount sufiicient to provide the bath with a pH of at least 8. Although not so specifically restricted the invention presently finds its best commercial applicability in the development of photographic gelatin layers.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention embraces the .use as a preservative for photographic black and white developing agents of a sulfite ester from a specific group of such esters plus an alkali in an amount suflicient to cause the pH of the bath to be at least 8. The sulfite ester is a compound selected from the group consisting of 1) 1, 2-ethylenesulfite O CH2CHz-O- 2) l-methyl-l,2-ethylenesulfite CH 0 oHi7Hosi 6 3) 1,2-dimethyl-l, 2-ethylene sulfite CH CH 0 H- H-O-ii 6 4) 1, 3-propy1enesulfite O CHzCH2CH-O (l 5) dimethylsulfite CH O S 0 CH According to the invention such a sulfite ester and alkali are used (a) in working solutions of black and white photographic developers, (b) in liquid black and white developer concentrates, that is to say, liquid compositions which are intended to be diluted, as with water, to form working solutions, (c) in liquid replenishes for black and white developers, these constituting solutions more concentrated than working solutions and which are intended to be added to working. solutions that are at least in part exhausted so as to bring them back to working strength, (d) in combined black and white developer/fixers of working strengths, these constituting so-called monobaths in which both developing and fixing takes place, and

(e) in black and white monobath concentrates which are intended to be diluted, as with water, to ttorm monobath working solutions.

The aforesaid sulfite ester novel preservative compounds of the present invention have the same stabilizing effect for photographic black and white developing agents, to Wit, inhibition of oxidation, in the presence of an alkali in an amount sufficient to establish a pH of at least 8 for a developing bath and/or monobath, as is conventionally supplied by alkali metal sulfites and/ or bisulfites, hydroxyalkylamine-sulfur dioxide addition products and ascorbic acid and its isomers that are presently known in the art, and said novel preservative compounds employed in an alkaline aqeuous medium having a pH of at least 8 are used pursuant to the present invention in the formulation of stable black and White photographic developers, e.g. working solutions, replenishers and liquid concentrates, such developers being inclusive of a black and white photographic developing agent and including conventional alkali-buffer systems such, for instance, as quaternary ammonium hydroxides, alkali metal carbonates, tetraborates, metaborates and hydroxides and the family of hydroxyalkylamines, either separately or in combination, in an amount suflicient to bring the pH of the developer to at least 8. Thus, the present invention embraces the use of the aforesaid novel preservative compounds in an alkaline aqueous solution having a pH of at least 8 for development of black and white photographs where said compounds act as preservatives under the said alkaline condition in combination with all kinds of standard additives for other conventional purposes.

The present invention includes the use with the aforesaid novel preservative compounds in an alkaline aqueous medium of at least pH 8 of all conventional black and white developing agents, particularly silver halide black and white developing agents, which are well known to the art. An exemplificative partial list of black and white photographic developing agents suitable for use, separately or in combination, with the new novel preservative compounds in alkaline aqueous working baths of at least pH 8, concentrates, replenishers and working monobaths of at least pH 8 includes: ,hydroquinone, chlorohydroquinone, 'bromo-hydroquinone, n-monomethyl-paminophenol sulfate and 1-phenyl-3-pyrazolidone and all its derivatives including 4,4-dimethyl-1-phenyl-3-pyrazolidone. Other conventional black and white developing agents can be employed without altering the scope of this invention. Developers so formulated may contain the known photographic developer addenda, i.e., restrainers: viz alkali metal chlorides, alkali metal bromides, alkali metal iodides; anti-foggants: viz benzotriazole, S-methylbenzotriazole, G-nitrobenzimidazole, l-phenyl-S-mercapto tetrazole, 2 anthraquinonesulfonic acid; sequestering agents: viz ethylenediamine tetraacetic acid and sodium hexametaphosphate; silver halide solvents: viz alkali metal thiosulfates and thioglycolates; various co-solvents: viz diethylene glycol; and gelatin hardening agents: viz formaldehyde and glutaraldehyde, as well as their bisulfite adducts.

It should be mentioned that developing compositions including black and white photographic developing agents, are not restricted solely to use with gelatin layers. They may be employed equally well, for instance, in silver halide-containing gelatin layers including gelatin extenders, such as carboxymethylated soy protein, or succinoylated hydroxyethyl cellulose, which replace a part of the gelatin in the photographic emulsion layer.

It has been found by employing combinations of the foregoing constituents, to wit, the black and white photographic developing agents, the novel preservative compounds, the alkali-buffer systems to obtain the minimum working bath pH mentioned, and, if desired, restrainers, anti-foggants, sequestering agents, silver halide solvents, co-solvents, and gelatin hardening agents, that high quality photographic black and white developers and developer-fixers with excellent stability have been prepared.

It has been ascertained that by utilizing the present invention the novel preservatives mentioned above can be packaged and stored in highly concentrated liquid form, indeed, even in the absence of Water. This is due to the fact that said novel preservatives are liquid in nature. Moreover, when they are poured into water they are readily water-miscible, being miscible easily within three to four minutes in ,general, which is the typical time required by persons skilled in the art to prepare working baths from concentrates and, in any event, in less than ten minutes which is the longest time feasible to be required by persons in this art for such mixing. Moreover, these preservatives are characterized by their ability to hydrolize rapidly upon addition to water, that is to say, within the period of time mentioned for mixing in an aqueous alkaline medium having a pH of at least 8. Moreover, the novel preservatives are of a medium viscosity in anhydrous form, e.g. having a viscosity not exceeding about 10 cps. Brookfield viscosity. The other components of the developer can also be packaged as liquid concentrates using high weight percentages thereof in a suitable liquid carrier which may or may not be water or an organic solvent. Using the conventional materials for black and white photographic developing agents and addenda, and the novel preservatives of the present invention, it is presently preferred to package a concentrate or replenisher, e.g. for a black and white developer, in three parts of which one part predominantly comprises the developing agent, the second part predominantly comprises the alkali/ alkaline buffer, a sequestrant and a wetting agent, and a third part predominantly comprises the sulfite ester preservative.

The concentrate form of the invention, and particularly that containing the novel preservative, has an order of viscosity which is low compared to, for example, a developer concentrate containing an alkanolamine-sulfur dioxide addition product as the preservative in an amount in the order of 25 g. per 50 ml. of developer concentrate along with proportionate amounts of developing agent and bufifering agent. Such a prior art developer concentrate has a viscosity of about 5250 centipoises at room temperature. This obviously makes preparation of a working developer bath or monobath extremely difficult and is unlike the instant novel sulfite ester concentrate which is particularly conducive to trouble-free mixing in water having a pH of at least 8.

The novel preservative compounds of the present invention are highly compatible with the other constitutents of the developing composition, i.e. are essentially inert thereto in the working bath. In particular, one of the advantages of employing any one or more of the sulfite esters of the present invention is that in combination with known gelatin hardening agents, namely, aldehydes and dialdehydes, a particularly stable working solution results.

It has been mentioned above that the novel preservative sulfite esters of the present invention can be used effectively in connection with aldehyde and dialdehyde gelatin hardening agents to form a particularly stable working developer or monobath solution. Specific aldehydes and dialdehydes useful in the present invention and mentioned by way of example are formaldehyde, glyoxal, glutaraldehyde, succinic dialdehyde, maleic dialdehyde, their derivatives and their bisulfite addition products.

A further advantage of the present invention is that it enables packaging of the alkyl ester in concentrated form in the total absence of water or the presence of insignificant amounts of water, which is particularly advantageous in selling to purchasers, these heretofore being accustomed to buying water solutions of sulfites with consequent extraneous bulk and shipping costs due to water that may now be substantially dispensed with.

As indicated previously, the concentration of the novel preservative sulfite esters can range up to by weight in the concentrate and/or replenisher. Water can be included if desired but is unnecessary because, as mentioned previously, these compounds dissolve and hydrolyze with suflicient rapidity in water having a pH of at 8 and preferably does not exceed 12 although the use of pI-Is from 12 to 14 is not excluded, such higher pHs under special circumstances being desirable.

In the preferred form of the invention the novel preservative sulfite ester should be present in an amount of at least 15 g. per liter, the maximum amount being up to the limit of solubility in the alkaline aqueous medium. Mention should be made that the alkali has multiple functions, one being in the pH range mentioned to assure hydrolyzation of the sulfite ester so as to form, i.e. liberate, a useful preservative sulfite ion, another being to solublize the sulfite ester and a third being as an activator for black and white developing agents.

The following examples will illustrate the use in accordance with the present invention of sulfite esters in a variety of actual developer formulations including different types of systems in varying proportions sufficient to act as a preservative for black and white developing agents in an alkaline aqueous medium having a pH of at least 8.

The solution prepared in Example I produces an excellent developer for both film and paper. Plus-X pan film is processed at 68 F. for only 2 minutes. Kodabromide F-2 paper is developed at 68 F. for 60 seconds. Both materials are fixed in a rapid acid fixing bath for 3 minutes and washed for 15 minutes at 68 F. and then dried in the normal manner. Example I can be packaged in any convenient way.

EXAMPLE II Water ml 700 1,2-ethylenesulfite (preservative) g 40.0 Hydroquinone (developing agent) g 5.0 4,4 dimethyl-l-phenyl-3-pyrazolidone (developing agent) g 0.125 Potassium carbonate [monohydrated] (buifer/ alkali) g 20.0 Potassium bromide (restrainer) g 0.2 Potassium hydroxide (alkali) g 4.4 Water to ml 1000 The above prepared developed is extremely stable to aerial oxidation and is well bulfered. Plus-X film and Kodabromide F-2 paper are processed at 68 F. for two minutes, followed by fixing and washings as described in Example I.

EXAMPLE III Water ml 700 Ethylenediamine tetraacetic acid (sequestering agent) g 2.0 Dimethylsulfite (preservative) g 15.0 Hydroquinone (developing agent) g 3.0 1-phenyl-3-pyrazolidone (developing agent) g 1.0 1-phenyl-S-mercapto-tetrazole (anti-foggant) g 0.02 2-methylaminoethanol (organic amine alkali) g 16.7 Water to ml 1000 This formulation will efiectively develop photographic printing paper similar to Kodabromide at 68 F. for 1 minute. Fixing and washing is as described in Example I.

EXAMPLE IV Water mL- 600 Ethylenediamine tetraacetic acid (sequestering agent) g 1.0 1,2-ethylensulfite (preservative) g 58.0 Hydroquinone (developing agent) g 20.0 Glutaraldehyde [50%] (hardener) g 8.0 4,4 dimethyl-1-phenyl-3-pyrazolidone (developing agent) g 2.0 Benzotriazole (anti-foggant) g 0.50 6-nitrobenzimidazole (anti-foggant) g 0.20 Potassium bromide (restrainer) g 8.0 Boric acid g 28.0 Potassium hydroxide (alkali-buffering system) g 31.0 Water to ml 1500 This stable, hardening formulation will develop both double and single coated X-ray film in 70 seconds at 90 F. The developed X-rays are fixed in an aqueous solution of ammonium thiosulfate and acetic acid fixer [a special fixer for automatic processing of X-ray film] for 35 seconds and washed for 60 seconds at 90 F. and dried.

EXAMPLE V Water ml 700 Ethylenediamine tetraacetic acid (sequestering agent) g 1.0 Dimethylsulfite (preservative) g 15.0 Hydroquinone (developing agent) g 4.0 4,4 dimethyl-l-phenyl-3-pyrazolidone (developing agent) g 1.0 Potassium carbonate (buffer/alkali) g 15.0 Potassium bromide (restrainer) g 0.25 5-methylbenzotriazole (anti-foggant) g 0.05 Water to ml 1000 The developer prepared from Example V will develop Plus-X film to a gamma of 1.02 in 5 minutes at 68 F. Kodabromide paper is developed in 2 minutes at 68 F. Both materials are fixed in a rapid acid fixer for 3 minutes and washed in running water for 15 minutes at 68 F. and dried in any conventional manner.

The foregoing combined developer/fixer (monobath) will completely process film similar to Plus-X pan in '8 minutes at 68 F. and dried. Excellent image quality results.

EXAMPLE VII Water ml 700 1,2-ethylenesulfite (preservative) g 15.0 Hydroquinone (developing agent) g 3.0 l-phenyl-3-pyrazolidone (developing agent) g 0.5 Tetramethylammonium hydroxide (25%) (alkali) g 12.5 Water to ml 1000 This bath will develop miniature film, such as Plus-X pan in 10 minutes at 68 F. to a gamma of 0.70. Fixing, washing and drying are done in the conventional manner.

This invention has been described in considerable detail with examples and references to specific formulations. It is understood that modifications and adjustments can easily be effected within the scope and spirit of this invention as described above and as defined in the following claims.

Having thus described the invention, there is claimed as new and desired to be secured by Letters Patent:

1. An aqueous black and white photographic developer for developing an exposed gelatin-silver halide black and white photographic emulsion layer, said developer including a black and White developing agent and a preservative constituting a compound selected from the class consisting of 1,2-ethylenesulfite; l-methyl-1,2-ethylenesulfite; 1,2-dimethyl-1,2-ethy1enesulfite; 1,2 dimethyl-l,2-ethylenesulfite; 1,3-propylenesulfite and dimethylsulfite for addition to a bath prepared by adding the developer to water with an alkali in an amount sufiicient to have a pH of at least 8, said preservative on an S basis being present in the developer in at least an equal molar ratio to the total number of mols of the black and white developing agent, and said preservative being present in an amount which, when added to the bath, constitutes from about 15 grams of the preservative per liter of bath to the limit of solubility of preservative in the bath.

2. A developer as set forth in claim 1 wherein the developing agent is a compound from the class consisting of hydroquinone, chloro-hydroquinone, bromo-hydroquinone, n-monomethyl-p-aminophenol sulfate and 1- phenyl-3-pyrazolidone and all its derivatives.

3. A developer as set forth in claim 1 wherein the alkali is present in an amount to cause the bath to have a pH of between 8 and 12.

4. A developer as set forth in claim 1 wherein the alkali is present in an amount to cause the bath to have a pH of between -8 and 14.

5. A developer as set forth in claim 1 wherein the alkali is a compound selected from the class consisting of quaternary ammonium hydroxides, alkali metal car- .bonates, tetraborates, metaborates and hydroxides and hydroxyalkylamines.

6. A developer as set forth in claim 1 which further includes a silver halide solvent.

7. A developer as set forth in claim 1 which further includes a gelatin hardener selected from the class consisting of aldehydes and dialdehydes.

8. A developer as set forth in claim 1 in which at least the preservative is present in liquid highly concentrated form of low viscosity and a water content not exceeding 20% by weight of the preservative.

9. A developer as set forth in claim 1 in which at least the preservative is present in liquid highly concentrated form of low viscosity and a water content not exceeding by weight of the preservative.

References Cited UNITED STATES PATENTS 2,363,777 1944 Downing et a1. 7666 J. TRAVIS BROWN, Primary Examiner E. C. KIMLIN, Assistant Examiner US. Cl. X.R. 96-66 

